In a semiconductor package assembly process, dicing refers to a process of cutting a wafer into a plurality of semiconductor chips using mechanical sawing with a blade or laser cutting. In other words, dicing refers to a process of separating a wafer into individual semiconductor chips so that the individual semiconductor chips can be mounted on a basic frame and encapsulated into a lead frame or a printed circuit package.
As semiconductor devices are developed to have higher capacity, higher speed, and smaller scale, low-K materials are increasingly used as an insulating material between metals. In general, a low-K material refers to a material having a dielectric constant that is less than the dielectric constant of silicon dioxide.
A method of dicing a wafer including a low-K material using mechanical sawing with a blade has a disadvantage in that during dicing, chipping, which is an event where semiconductor chips partially break, and cracking, which is an event where semiconductor chips are cracked, may occur. Accordingly, there is a demand for a method of dicing a wafer which can prevent chipping or cracking in a semiconductor package assembly process.
In order to fulfill the demand, a method of dicing a wafer using laser cutting or plasma etching, instead of mechanical sawing with a blade, has been proposed because even if the rotational speed of the blade is controlled when cutting a wafer, chipping and cracking may be minimized but high quality cut semiconductor chips may not be obtained. Also, if the rotational speed of the blade is controlled, the number of semiconductor chips obtained per unit time may be reduced, thereby lowering productivity.
However, a method of dicing a wafer using laser cutting has a disadvantage in that, when the wafer is grooved along scribe lines or is completely cut along the scribe lines, active surfaces of semiconductor chips should be coated with an expensive coating material in order to prevent silicon particles from being fused onto the active surfaces of the semiconductor chips. Also, the method of dicing the wafer using the laser cutting has another disadvantage in that, since a laser used to groove the wafer and a laser used to completely cut the wafer are different from each other, when the wafer is completely cut along the scribe lines, a die attach film (DAF) which is located in the backside of the wafer is not easily cut.
When a wafer is cut along scribe lines, a method of dicing a wafer using plasma etching requires an etch mask in order to prevent surfaces of semiconductor chips from being etched. The method of dicing the wafer using the plasma etching has a disadvantage in that the etch mask is formed using photolithography in a general wafer manufacturing process and thus makes semiconductor packaging complex and increases manufacturing costs.